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GM 2.2 ECOTEC cylinder head

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I have a copy of the GM performance parts compact car build book it talks about you can machine the stock head to handle up to 900 HP. But the combustion chamber has to be staked. What are they referring to when saying the combustion chamber has to be staked? I'm a mechanic by trade but I'm trying to learn the performance side of things.

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I was totally confused by your use of the word "stacked", but what it says (thanks to your picture), is "staked" -- so it could refer to an installation procedure for a valve seat.

Googling just finds reference to a recall on the cam cover where the lack of heat staking (ie melting a plastic boss) of a splash shield, was leading to increased oil consumption.

Yeah my bad I miss typed but still like you said I can't really find anything just searching on the internet.

I suggest you contact the author/publisher of the book and ask for clarification.

There is some folklore about valve seat staking...


Thank you for the link but the book was a official book written by Chevrolet performance themselves. It was last printed in like 2008. Not really anyone I can contact.

Don't give up trying. It amazing who you can talk to by calling and asking...

Perhaps start with one of the GM performance dealers and ask them for contacts in GM Performance...


As with the others, not exactly sure what they meant by "combustion chamber" staking, but I'm aware of the process being used for valve seats - but not a fan of the process. Could it also be referring to some process for retaining heat gasket seal?

Seat walk, and even dropping, isn't unknown as the head is heated and flexes slightly under the combustion pressures - this is worsened if the interference/press fit is insufficient, or the seat is short which means the clamping force retaining the seat is concentrated over a narrower area.

As per some of the comments made in the links, the best option may be to use a seasoned head which may be expected to have 'settled' and machine it for oversized, and deeper, seat inserts. They may be required, anyway, with larger diameter valves.

Yeah I think they were referring to the valve seats, which seems like a terrible idea. The main thing was I had no idea what they were talking about at first. I know what they talking about now. So thank you guys for the input.

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